Ether esters



Patented Sept. 11, 1945 I "UNITED STATES PATENT OFFIC ETHER ESTEBS Donald Drake Coilman, Lindamere, Del, assignor to E. I. -du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing.

Application November 28 1942, Serial lilo. 467,209

4 Claims. (01. 260-484) This-invention relates to l-acyloxyethyl ethers of alpha-hydroxy acid esters and a process for preparing the same. 7

This invention has as an object the provision of a process for making new ether esters. Another object comprises a. novel and useful class of compounds-that of 1-acyloxyethyl ethers of alpha-hydroxy acid esters. A further object is the preparation of new plasticizers for cellulose esters and synthetic resins. Other Objects will appear hereinafter.

These objects are accomplished by the following invention wherein a vinyl ester, free from aliphatic unsaturation and from active hydrogen and preferably a neutral ester, of an organic carboxylic acid is reacted with an alkyl ester of a saturated alpha-hydrcxy acid in the presence of a mercuric catalyst under substantially anhy-' drous conditions at an elevatedtemperature, i. e.,

30 to 150 C., but preferably 70 to 100 C.

Th more detailed. practice of the invention is illustrated by the following example wherein parts given are by weight. There are, of course,

many forms of the invention other than this she-- cific embodiment.

Example In a vessel provided with heating elements and equipped with a reflux condenser, stirrer, thermometer, andan inlet for introducing liquids, were placed 500 parts of methyl hydroxyacetate and 50 parts of anhydrous mercuric phosphate. The suspension was stirred and heated to 75 to to" 0., when 550 parts of vinyl acetate was added through the inlet tube at such a rate that the addition required about 6 hours. The reaction mixture was stirred for an additional 2 hours at 75 to 80 C. At the end of this time,

, the temperature 'was raised to 100 C. and the stirred mixture maintained at this temperature for 10 hours. At the end of this time the heating ing methyl hydroxyacetaie, isobutyl lactate, cyclohexyl alpha-hydroxybutyrate, benzyl malate, furfuryl alpha-hydroxyisobutyrate, dodecyl alpha-hydroxyvalerate, ethyl mandelate, isopropyl benzilate, propyl tartrate, butyl citrate, t-butyl" mucate, ethyl furfurylhydroxyacetate, methyl cyciohexylhydroxyacetate, methyl p-chicromandelate, and, in general, any alkyl ester of a saturated alpha-hydroxy carboxylic acid. The alpha carbon, bearing as'it does both the hydroxyl and carboxyl, cannot be aromatic but the rest oi the molecule may be aliphatic, alicyclic, aromatic, or heterocyclic, monocarboxylic or polycarboxylic. Neutral esters-are preferred in the case of polycarboxylic acid esters. The alkyl esters of hydroxy fatty acids are preferred reactants.

For reaction with the methyl hydroxyacetate and, in general, for reaction with the alkyl esters cule is hydrocarbon except for the carboxyl groupor groups are preferred. In the case of polyand stirring were discontinued, and the liquid portion after separation from the solid catalyst was tractionally distilled at 2 to 3 mm. mercury. In this manner, 351 parts of the l-acetoxyethyl ether of methyl hydroxyacetate was obtained which distilled at 66 to 67 C./2 to 3 mm. A

sample on analysis had the following properties:

Calcu- Med Found 0 "percent" 47. 83 47. 74 do 0. 88 7. 8 Sapcniilcstion number" 88. 08 88. i0 rt 1. 12% Nu l. 4170 Molecular refraction 39. 48 30. 43

In place of the, methyl hydroxyacetate of the i above example there may be employed any alkyl eater oi a saturated alpha-hydroxy acid includcarboxylic acids, the neutral esters are preferably employed, e. g. divinyl adipate or vinyl ethyl adipate. Vinyl esters of saturated fatty acids, e. g., the'formate, acetate, propionate, stearate, are preferably employed. The vinyl ester is of course the monomeric ester.

In the process of this invention catalysts may be employed. Those catalysts which catalyse the formation of ethylidene derivatives in the reac- .tion of hydroxy compounds with acetylene are preferred, including mercuric phosphate, inercuric acetate, mercuric sulfate, and mixtures oi i i l mercuric oxide with boron trifluoride in the form of complexes of the latter with such compounds as ether, methanol acetic acid, and water (BE-H2O and El 's-2&0), but preferably with methanol. Mixtures of mercuric oxide with silicon tetrafluoride complexes (with water but preterably with methanol) can also be used. The reaction should be carried out under substantially anhydrous conditions.

The temperature of the reaction maybe 30'- 15ii 0., the preferable range being '70100 C. In case one of the reactants is low boillnl. i. e., in the range of co C., the preierable maxio mum temperature will be the reflux temperature of the low boiling reactant. In some cases, such as with. vinyl formate, or the use of diethyl ether as a solvent, the preferable range is above the boiling point of the mixture and necessitates BCOO-GHO-CH-C0Bfi wherein R is hydrogen or an organic radical free from active hydrogen and ethylenic and acetylenic maturation and is preferably hydrocarbon. R is hydrogen or an organic radical free from ethylenic and acetylenlc unsaturation and preferably saturated hydrocarbon or hydrogen and R: is an alkyl radical. They are oily liquids to low melting waxy solids which on hydrolysis with dilute (e. g. 5%) aqueous mineral acid'ihydrochloric or sulfuric) e. 8., by refluxing one hour yield acetaldehyde, an alkanol RFOH, an acid 00 the presence of a mercuric catalyst at 30-100 C.

R-CO-OH, and an alpha-hydroxy acid R -CH0H-C0-OH where R. R and R have the significance above given. Thus, the product oirthe example, the 1- acetoxyethyl ether 0! methyl hydroxyacetate yields acetaldehyde. methanol, hydroxyacetic acid and aceticacid.

The i-acyloxyethyl ethers oi alpha-hydroxy acid esters may be employed as intermediates which by pyrolysis are converted to the vinyl others 01' alpha-hdroxy acid esters.

The higher molecular weight compounds may be employed as plasticizers for cellulose derivatives such as cellulose acetate and cellulose nitrate, or for other common plastics such as polyvinyl chloride or polymethyl methacrylate.

The term saturated is used herein to express freedom from ethylenic and acetylenic unsaturation.

The term active hydrogen (Whitmore 1937, page 214) is used to represent hydrogen shown in the Zerewitinofi method.

The above description and example are intended to be illustrative only. Any modification or or variation therefrom which conforms to the spirit oithe invention is intended to be included within the scope of the claims.

. What is claimed is:

1. The process which comprises reacting methyl hydroxyacetate with vinyl acetate in the presence oi mercuric phosphate at -l00 C. and under 3 anhydrous conditions.

2. The l-acetoxyethyl ether of methyl hy-J droxyacetate.

3. The process which comprises reacting an alkyl ester of an alpha-hydroxy alkanoic acid in under anhydrous conditions with the vinyl ester of analhanoic acid.

4. An ether ester of ethylidene glycol having one hydro'xyl etheriiied with an alpha-hydroxy alkanoic acid alkyl ester and the other hydroxyl estcrifled with an alkanoic acid. v

' DONALD DRAKE COFFMAN. 

